With the progress in the medical science and technologies, many types of artificial organs have been developed to substitute for patients' impaired organs. A human body implant electrode assembly is designed to substitute the excitation of bioelectric signals by using current stimulation, so as to correct organs that could not work normally. Among others, the technique of cochlear implantation has reached a highly matured stage. As it is known, the human ear can hear because the tympanic membrane is vibrated by acoustic waves, and the auditory ossicles transmit vibration signals to the cochlea, and then, the frequencies of vibration signals are analyzed in the cochlea to produce bioelectric signals corresponding to the bands of the auditory waves. Finally, the bioelectric signals form hearing sense at the cerebral cortex. The cochlear implant is designed based on the aforementioned concept about hearing. For this purpose, the cochlear implant includes a speech processor to convert the acoustic waves into frequency signals. The frequency signals bypass the tympanic membrane and the auditory ossicles, so that stimulating currents corresponding to different frequencies are directly fed into the cochlea to stimulate corresponding auditory nerves. That is, the normal procedures for generating bioelectric signals are replaced by the operating procedures of the cochlear implant.
The cochlear implant is an electrode array consisting of a flexible member carrying a plurality of electrodes thereon. The cochlear implant is connected to an external speech processor, which performs signal process to convert sounds into current signals. Then, the electrodes are controlled to produce stimulating currents to replace the human body's bioelectric signals and thereby reconstruct a patient's hearing. For example, in a normal condition, the apical (deep) area of the cochlea serves to process the low-frequency band of the acoustic signals. Therefore, when the speech processor has separated the low-frequency signals from the acoustic waves, the electrodes near the apical (deep) area of the cochlea are driven to produce stimulating currents to replace the bioelectric signals.
However, according to the currently available implant surgery operation and equipment, the implantation of cochlear implant is still largely relied on the microsurgery, and therefore encounters with many bottlenecks. Please refer to FIG. 1 that is a schematic view of a conventional cochlear implant, which includes a flexible implant 200. Since the human cochlea 100 is a coiled structure, when performing surgery operation to implant the flexible implant 200 into the cochlea 100, the surgeon's skill and experience are very important factors in the operation. In the event the flexible implant 200 is not correctly implanted, the fragile cochlea wall or membrane inside the cochlea is dangerously subject to lesion, as the lesioned area 300 shown in FIG. 1. Please further refer to FIG. 2 that is another schematic view of the conventional cochlear implant. Another very common problem in the cochlear implant surgery operation is that the flexible implant 200 must be very soft and is therefore frequently subject to undesirable bending in the process of implantation, as the bent portions 310 shown in FIG. 2. The bent flexible implant 200 will result in interrupted signal transmission, mutual interference between stimulating currents, incorrect electrode positions, etc. Even if the cochlear implant has been completely implanted into the cochlea, it is possible the distances between an axis of the cochlea and different portions of the flexible implant 200 are not uniform, as the non-uniformly spaced areas 320 shown in FIG. 3, which is still another schematic view of the conventional cochlear implant. The problem of non-uniformly spaced areas 320 might occur during the implant surgery operation or after strenuous exercise of the user. Due to the existence of non-uniformly spaced areas 320, the user will be particularly sensitive to sounds fallen in some frequency bands while insensitive to sounds fallen in some other frequency bands. Even if the implant surgery operation has been successfully performed, the cochlear implant will still face some other problems after being used for a period of time. For instance, electrodes for some important and often needed bands and electrodes located at positions with the auditory nerves in a relatively good condition are subject to bending or damage because these electrodes often have electric currents flowed therethrough. Under this circumstance, the patient would require another surgery operation to replace the cochlear implant. US Patent Publication No. 20060052656, U.S. Pat. No. 6,263,225B1, and U.S. Pat. No. 6,475,223B1 all disclose implant techniques relating to human body.